Yeah, there's quite a nice large chunk of changes coming up. The code for the front-end has changed a lot from the version that is on the Google Play store (not to mention it has been made more modular). Also SonicAdvance1 has done (and is still doing) a pretty phenomenal job with his ARM JIT recompiler, which is much better now compared to the one on the Play store.

Just to give you an idea of what changes to the UI have been made, here's a few screenshots. Imgur Gallery.
Obviously some things are subject to change, so don't take that gallery as the final version of the UI.